title: Altered gene expression in early osteochondrosis lesions.
abstract: Osteochondrosis is a condition involving defective endochondral ossification and retention of cartilage in subchondral bone. The pathophysiology of this condition is poorly characterized, but it has been proposed that the fundamental defect is failure of chondrocyte hypertrophy. The aim of the current study was to characterize phenotypic changes in chondrocytes associated with the initiation of osteochondrosis. Early lesions were induced in an equine model of osteochondrosis by feeding foals a high energy diet for 8 or 15 weeks. Lesions in articular-epiphyseal growth cartilage were examined histologically and by quantitative PCR analysis of expression of a number of genes representative of pathways that regulate chondrocyte behavior during endochondral ossification. There were more cells present in clusters in the lesions compared to normal articular cartilage. Expression of matrix metalloproteinase-13, type I collagen, type X collagen, and Runx2 mRNA was significantly greater in the lesions compared to normal cartilage from the same joint. Expression of vascular endothelial growth factor, type II collagen, connective tissue growth factor, aggrecan, Sox9, and fibroblast growth factor receptor 3 mRNA was not significantly different in lesions than in control cartilage. These observations suggest that osteochondrosis does not result from failure of chondrocytes to undergo hypertrophy.
authors.affiliation: School of Veterinary Science, University of Melbourne, Parkville, VIC 3010, Australia.
authors.forename: Michiko
authors.initials: M
authors.lastname: Mirams
authors.forename: Liliana
authors.initials: L
authors.lastname: Tatarczuch
authors.forename: Yasser A
authors.initials: YA
authors.lastname: Ahmed
authors.forename: Charles N
authors.initials: CN
authors.lastname: Pagel
authors.forename: Leo B
authors.initials: LB
authors.lastname: Jeffcott
authors.forename: Helen M S
authors.initials: HM
authors.lastname: Davies
authors.forename: Eleanor J
authors.initials: EJ
authors.lastname: Mackie
mesh_terms: D000818:Animals; D024043:Collagen Type II / Q000235:genetics; D055513:Connective Tissue Growth Factor / Q000235:genetics; D015870:Gene Expression; D006736:Horses; D053509:Matrix Metalloproteinase 13 / Q000235:genetics; D055034:Osteochondrosis / Q000378:metabolism* / Q000473:pathology; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics
chemical_list: D024043:Collagen Type II; D042461:Vascular Endothelial Growth Factor A; D055513:Connective Tissue Growth Factor; D053509:Matrix Metalloproteinase 13